1. UPMC Univ Paris 06, Institut Parisien de Chimie Moléculaire, UMR CNRS 7201, Equipe glycochimie, C181, 4 place Jussieu, 75005 Paris, France, Department of Chemistry, The University of York, Heslington, York, U.K., Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, Canada, and Centro de Investigaciones Biológicas, CSIC, Madrid, Spain